Trauzl lead block test

[1] The hole is then topped up with sand, and the sample is detonated electrically.

After detonation, the volume increase of the cavity is measured.

The result, given in cm3, is called the Trauzl number of the explosive.

The Trauzl test is not useful for some modern higher-powered explosives as their power often cracks or otherwise ruptures the lead block, leaving no hole to measure.

[2] A variant of the test uses an aluminium block to avoid exposure of participants to lead-related hazards.

Trauzl lead block before and after a test (1 – sand | 2 – Explosive and detonator | 3 – lead)